Answer:
C) 3,000 kg m/s
Explanation:
We can consider the horizontal velocity of the motorcycle to be zero, since it rolls off the edge of the cliff very slowly. So, we only need to find the vertical velocity at the time of the impact with the ground.
The vertical velocity of the motorcycle at time t is given by (free-fall motion):

where
is the initial vertical velocity (zero, since the motorcycle is not moving)
g = 9.8 m/s^2 is the acceleration due to gravity
t is the time
Since the motorcycle hits the ground after t = 3 seconds, we have

And since we know its mass, m=100 kg, we can find its momentum:

and the negative sign simply means downward direction.
Answer:
The question is incomplete. However, I believe, it is asking for the acceleration of the elevator. This is 3.16 m/s².
Explanation:
By Hooke's law, 
F is the force on a spring, k is the spring constant and e is the extension or compression.
From the question,

This is the force on the mass suspended on the spring. Its acceleration, a, is given by



This acceleration is more than the acceleration due to gravity, g = 9.8 m/s². Hence the elevator must be moving up with an acceleration of
12.96 - 9.8 m/s² = 3.16 m/s²
Answer: Black hole.
Explanation:
As the massive star "compacts" under its own gravity, it triggers a massive supernova, after this point the remains of the star can become a neutron star, which is a very compact star made primarily, as the name says, of neutrons. The other possibility is a black hole, which is a finite region of space wherein it's interior there is a big concentration of mass, which creates a gravitational field strong enough that there is no particle that can escape it.